Wood Stove Clearance Calculator
Enter your stove's manufacturer-rated clearance and your heat shield type. Get back every required clearance distance — walls, floor, ceiling, and stovepipe — based on NFPA 211 reduction tables.
🔥 Clearance Calculator
Find the stove's rated clearance on the certification label on the back or underside of your unit. This is the starting clearance the calculator reduces based on your shield type.
How to Find Your Stove's Rated Clearance
The rated clearance is printed on the EPA certification label permanently affixed to your stove — usually on the rear panel or underside. The label will say something like:
If your stove label lists different clearances for rear versus sides, use each number for its respective surface. The calculator above uses a single value for both — if they differ, run the calculator twice (once for rear, once for sides) to get both answers.
Understanding the Reduction System
NFPA 211 Table 8.2.1.2 allows clearance reductions when approved heat shields are installed between the stove and combustible surfaces. The shield works by intercepting radiant heat and dispersing it through convection — the air gap is critical to this process.
| Shield Type | Reduction | Air Gap Required | Example: from 36 in. |
|---|---|---|---|
| None | 0% | — | 36 in. |
| Single sheet metal + 1 in. gap | 33% | 1 in. behind | 24 in. |
| 3½ in. masonry + 1 in. gap | 33% | 1 in. behind | 24 in. |
| Sheet metal + mineral wool | 50% | None | 18 in. |
| Two-layer sheet metal + 1 in. gap | 66% | 1 in. between | 12 in. |
| Listed system | Up to 67% | Per instructions | As low as 12 in. |
The minimum clearance after any reduction is 12 inches for most stoves. Even with a listed reduction system, no clearance below 12 inches is approved under NFPA 211 for most solid fuel appliances unless the stove's own certification specifically lists a lower value.
Stovepipe Clearances — Separate from Stove Body
The stovepipe connecting your stove to the chimney has its own clearance rules that are independent of the stove body clearances:
- Single-wall stovepipe: 18 inches from all combustible surfaces. Cannot pass through walls, ceilings, floors, or attic spaces.
- Double-wall listed stovepipe: 6 inches from combustibles (check the listing — some go lower).
- Class A chimney pipe (through-ceiling sections): 2 inches from combustible framing, using a listed support box or thimble.
The stovepipe clearance applies along the entire length of the pipe — not just at the connection points. If your single-wall pipe passes within 18 inches of a bookshelf, wall stud, or ceiling beam anywhere along its run, that section fails.
Hearth Pad — Floor Protection Sizing
Use this table to determine the minimum hearth pad size for your stove:
| Firebox Opening Size | Front Extension | Side Extension | Rear Extension |
|---|---|---|---|
| Less than 6 sq ft (most freestanding stoves) | 16 in. | 8 in. each side | 8 in. |
| 6 sq ft or larger | 20 in. | 12 in. each side | 12 in. |
Measurements are from the edge of the firebox opening — not the stove's outer body. See the full Hearth Pad Guide for material requirements and construction options.
Print your results. After running the calculator, use your browser's print function to save the output as a PDF. Bring it to your permit application and keep a copy on-site for the inspector.
Frequently Asked Questions
Yes — always use the number on your certification label, even if it's lower than 36 inches. Modern stoves routinely list 12–16 inch clearances from the factory, achieved through internal air circulation design. Enter that number as your "stove rated clearance" in the calculator above. The label clearance is the legal standard for your specific unit.
No. NFPA 211 reduction methods are not stackable. You apply the single best-qualifying method and use that reduction. The two-layer sheet metal method (66% reduction) is the maximum for field-built shields. For further reduction below that, you need a manufacturer-listed clearance reduction system, which has been laboratory-tested as a complete assembly.
You have two options: install a stove that is listed with smaller factory clearances (many modern stoves list as low as 4–8 inches with their own integral heat shields), or use a listed clearance reduction system that brings the required distance down to 12 inches. If 12 inches still cannot be achieved in the space, that location is not code-compliant for a wood stove installation and a different location — or a different heating solution — is needed.
Only if it meets the NFPA 211 specification: 3½ inches of solid masonry with a 1-inch air space between the back of the masonry and the combustible wall behind it. Decorative stone veneer (which is typically ¾–1 inch thick) does not qualify for clearance reduction. The 1-inch air gap must also be open at top and bottom to allow convective airflow — a sealed decorative surround provides no thermal protection benefit under code.